1) Field of the Invention
The present invention relates to a vehicle object recognition apparatus which is designed to emit or radiate transmission waves throughout a predetermined angular range in each of vertical (vehicle-height) and horizontal (vehicle-width, lateral) directions from one vehicle to recognize an object in front of the vehicle on the basis of reflected waves thereof, and further to an inter-vehicle control unit.
2) Description of the Related Art
So far, for example, as disclosed in Japanese Patent Laid-Open No. 2002-40139, there has been proposed an object recognition apparatus designed to emit an optical wave or millimetric wave to detect a reflected wave thereof for recognizing an object existing in a forward direction. For example, such an apparatus is applicable to an apparatus made to detect a vehicle in a forward direction and issue an alarm, an apparatus made to control a vehicle speed for keeping a predetermined distance (inter-vehicle distance) between oneself (this vehicle) and the vehicle ahead, or the like. That is, it has been incorporated into applications involving the recognition of a vehicle existing in a forward direction.
The aforesaid object recognition apparatus is designed to emit a plurality of transmission waves forwardly throughout a predetermined angular range in each of vertical and horizontal directions from one vehicle for recognizing a preceding vehicle three-dimensionally on the basis of the reflected waves thereof. At this time, in a case in which a reflecting object (reflection-causing object) lies at a height or in a range where a vehicle does not exist normally, for a non-vehicle (an object other than vehicles) recognition, different transmission wave output levels are set according to transmission wave outputting regions or zones to make it harder for the non-vehicle to be identified as a preceding vehicle or a non-vehicle discrimination is made through the use of a non-vehicle decision map for distinguishing a non-vehicle from a vehicle. In this case, the non-vehicle decision map signifies a three-dimensional map in which a reflected wave reception intensity range for distinguishing between a non-vehicle and a vehicle is set in a state associated with an existing region of a reflecting object in a case in which a vehicle width, a vehicle height and a vehicle forwarding direction are taken as X, y and Z axes, respectively.
However, as mentioned above, for the transmission wave output level to be changed according to a transmission wave outputting region or for a non-vehicle to be discriminated through the use of the non-vehicle decision map, there is a need to mount a radar unit, which detects the reflected waves, on a vehicle with an extremely high accuracy. In other words, if a transmission wave output axis is shifted depending on the mounted state of the radar unit, difficulty is encountered in making the discrimination between a non-vehicle and a vehicle, for that a region in which a reflecting object exists cannot be discriminated with accuracy.
For this reason, in a conventional technique, when a radar unit is mounted on a vehicle, an operator adjusts the mounting angle thereof and others through the use of an adjusting bolt or the like. However, the adjustment operation becomes more difficult as the tolerance (tolerable range) of the mounting angle of the radar unit is made smaller (narrower), and it takes time, which leads to an increase in manufacturing cost.
Furthermore, so far, there has been known an inter-vehicle distance control unit made to measure a distance from a preceding vehicle and a relative speed thereto for keeping an inter-vehicle distance constant, wherein the probability that a preceding vehicle and oneself (this vehicle) exists on the same lane is calculated to select a preceding vehicle as an object (counterpart) of inter-vehicle distance control on the basis of the calculated probability, as exemplified in Japanese Paten Laid-Open No. HEI 8-279099. In more detail, in the inter-vehicle distance control unit disclosed in this document, for example, when a plurality of objects (bodies) are detected, the position of each of the objects is put on a one's-lane probability map set in advance through actual measurements to obtain the probability that each of the objects exists on the same lane as that of this vehicle (in other words, the priority rate in handling as an object of inter-vehicle distance control) for selecting the object having the highest probability as a preceding vehicle which is a counterpart for the inter-vehicle distance control. The inter-vehicle distance control is implemented to maintain the distance with respect to the selected preceding vehicle.
The aforesaid one's-lane probability map to be used for the conventional inter-vehicle distance control unit is composed of a plurality of areas and a probability of a preceding vehicle existing on the same lane of that of oneself being allocated or given to each area. However, if this one's-lane probability map is applied to both a stopping (stationary) object and a moving object recognized through a forward obstacle recognition processing, the following problems arise.
For example, in a case in which an obstacle recognized through the forward obstacle recognition processing is a stopping object, since the stopping object is recognized as a stationary thing, if it exists outside its own lane, the probability of the existence on the same lane can be set at a low value without depending on the distance up to the obstacle. However, in a case in which an obstacle recognized through the forward obstacle recognition processing is a moving object, even if it exists outside its own lane, there is a possibility that the moving object cuts into the lane immediately before oneself. For this reason, in particular, when the distance to the obstacle is short, there is a need to set the probability of the existence on the one's lane as that of this vehicle to a high value in some degree.
Thus, since the conventional one's-lane probability map is used for both the stopping object and moving object recognized through the forward obstacle recognition processing, the probability is not set in conjunction with a state of the object, which makes it difficult to precisely select an object for the inter-vehicle distance control.